Alternatives to Car Rental (if any) - Detroit to L.A.

I need to travel from Detroit to Los Angeles.

I'm going to be flying out of LAX to Oahu and living in Hawaii indefinitely. I'll be selling my car to fund part of the trip. I've looked at zipcar, as well as some other alternatives to car rental...

Any advice? Car rental sites are giving me prices to the tune of $900+ (not including fuel) to travel from Detroit to Los Angeles, that seems up there to me.

Any advice is greatly appreciated.